Async modbus serial connection error

[amagyar37]

Hi Experts,

I used this simple example to create an asynchronous task for reading modbus on com port:
https://pymodbus.readthedocs.io/en/latest/source/examples.html

When I try to use the serial port to connect to a modbus rtu device I got an error (see the picture attached).

By the way, modbus tcp works fine.

Please help me how to solve this issue.

Thanks,
Andras

[amagyar37]

Hi,
I forgot to add that I use Win 11.
Thanks,
Andras